Apparatus for ripening fruit and the like

ABSTRACT

A process and apparatus for accelerating the ripening of unripe fruits in boxes having air flow openings in the walls thereof, such as bananas, tomatoes, melons, pears, avocadoes, and the like, wherein the fruit is subjected to a timed initiating stage at temperatures of 68* to 95* F. in the presence of ethylene gas, and may then be subjected to subsequent stages of maturing, and of terminal temperature conditioning at selected temperatures, and times to achieve improved uniformity of ripening and prolonged shelf life. The apparatus includes timers, temperature sensors and heating and cooling means interconnected to automatically cycle the fruit through the ripening program.

United States Patent McDonnell et al. Aug, 15, 1972 APPARATUS FORRIPENING FRUIT 2,71 1,471 6/ 1955 Sussman ..99/154 AND THE LIKE3,183,683 5/1965 Reiter et al. ..99/154 UX I 3,234,028 2/1966 Dunham etal ..99/100 UX [72] Invemms' ifgf h f g. fl 3,368,873 2/1968 Fuller eta] ..99/271 x 3,400,650 9/1968 Burg ..99/154 x 3,459,116 8/1969McDonnell ..99/239 [73] Assignee: Banana Control, Inc., New Orleans,3,592,665 7/1971 Macrill ct al ..99/239 X Primary ExaminerWalter A.Scheel [22] Filed July 1970 Assistant EraminerArthur 0. Henderson 21 AWL0 20 Attorney-Mason, Fenwick & Lawrence Related US. Application Data 57]ABSTRACT [60] Division of Ser. No. 767,426, Oct. 14, 1968, A process andapparatus for accelerating the ripening Pat. No. 3,620,765, which is acontinuation-in- 1 of unripe fruits in boxes having airflow openings inpart Of Ser. No. 523,327, Jan. 27, 1966, abanthe walls thereof, such asbananas, tomatoes, melons, do d, pears, avocadoes, and the like, whereinthe fruit is 1 subjected to a timed initiating stage at temperatures of52 us. Cl ..99/239, 99/103 6 1 in the Presence of ethylene gas, and y[51] Int. Cl ..B65g 1/00 be Subjected subsmluent Stages of maturing,

[58] Fidd of Search 99/239, 259, 271, 339, 100 and of terminaltemperature conditioning at selected 99/154 103 temperatures, and timesto achieve improved uniformity of ripening and prolonged shelf life. The[56] References Cited apparatus includes timers, temperature sensors andheating and cooling means interconnected to auto- UNITED STATES PATENTSmatically cycle the fruit through the ripening program. 2,625,095 l/1953 Julian ..99/259 5 Claims, 8 Drawing Figures PATENTEDAUE 15 1912 saw1 or 6 21': ila. Lul, 300. b

{I II 111 PATENTEDAUG 15 I972 3.683, 788

SHEET 3 [IF 6 III I 1 11/1/11 1 Ila Ho.

PATENTEDAUG 15 1972 SHEET 5 BF 6 APPARATUS FOR RIPENING FRUIT AND THELIKE This is a division of application Ser. No. 767,426, now US. Pat.No. 3,620,765, filed Oct. 14, 1968.

Application Ser. No. 767,426 is a continuation-inpart of my earlierapplication Ser. No. 523,327, now abandoned filed Jan. 27, 1966 andentitled BANANA-MATIC.

BACKGROUND AND OBJECTS OF THE INVENTION Under previous procedures forripening bananas, the bananas were received from shipment in the form ofstemmed fruit or hands, as distinguished from present shipping methodswherein the fruit is boxed. These bananas were placed in warehouses forripening, and after a period of time were then delivered from thewarehouse to the retail stores where the bananas were to be displayedfor sale. The warehouses required a large number of ripening rooms, sothat the bananas could be assigned to individual rooms based on the dateof delivery of the bananas to the retail stores. The ripening scheduleswere customarily 5 to 8 days from date of delivery of the bananas to theripening rooms. A ripening room employee must supervise the regulationof temperatures in the individual ripening room in accordance with aselected schedule, requiring constant supervision of the banana ripeningoperation. Effort was normally made to maintain the temperatures withinthe ripening room in the range of 61 to 65 F., so that the bananas donot over-heat and spoil before delivery to thestore. Initially, theripening room employee, after storage of the bananas in the ripeningroom, brought all of the pulp temperatures to 60 F. or higher, but neverexceeded 65 F. After most of the bananas have a pulp temperature of 60F. or higher, pure ethylene was introduced into the ripening room for 24hours. During this time the doors remain closed and were not openeduntil the 24-hour period was over. At the same time the gas was injectedinto the room, the room temperature was raised to 65 F.

After the 24-hour period, the ripening room doors were opened forventilation and blowers flushed out the ethylene gas and carbon dioxidebuilt up in the rooms. After the rooms were vented, the doors 'wereclosed and the room temperature was lowered to 62 or 60 F., depending onthe ripening schedule. Sometimes the temperature range of 58 to 64 wasused .without ethylene gas, but the ripening cycle in such cases was 6to 8 days. After the fourth day, when the ethylene gas was used, thebananas were a color No. 3 (more green than yellow) and were thentransported to the stores. However, most deliveries from the warehousetook place 5, 6, 7 or 8 days from the time the bananas were firstintroduced into the ripening room. Since the biochemical processes orreactions for ripening of the bananas had already been initiated at thetime the rooms were vented, aging of the bananas had already begun,induced by excess hormone resulting from its accumulation before andafter the ethylene gas was injected into the ripening rooms or itsindiscriminate addition, so that rapid degradation of the chlorophyllpigments were attained when desired. The frequent result was thatoverripe bananas of uneven color were transported to the stores and,because of their soft condition, were heavily bruised and scarred by thepressure of top hands of bananas on the bottom hands of bananas, causingpermanent pulp and peel bruise. The bananas were delivered to the storesand stored in the back room where the temperature is normally to F. inthe summer, and 40 to 45 in the winter. This produced many dehydratedand cooked bananas in the summer, and many underripe and chilled bananasin the winter. Both chilling and overripening cause dessication andresult in tasteless, mealy bananas In accordance with conventionalpackaging and shipping methods, the bananas are stored in stacked boxform in the ripening rooms. Attempts are made to control temperature byair diffusion, but when high air temperatures are used to achieveripening of the bananas, great temperature variations are found to occurin the individual boxes, resulting in a higher pulp temperature than theroom air temperature in some of the boxes. These non-uniform high heatareas are caused by the bananas giving off heat which is trapped in themiddle and bottom boxes in each stack and the interior fruit in allboxes due to the ineffectiveness of the diffusion method of air flowused in such ripening rooms.

While it is possible to remove the fruit from the boxes for ripening, todo so frequently bruises the fruit, and in any event it is most timeconsuming.

Thus, under present mass handling conditions, it is particularlydesirable to treat and handle all fruit while boxed in the usualcardboard boxes used for shipping. The size of these boxes varies withthe type of fruit, but for bananas, the size is usually 21 X 16 X 10inches with openings which serve as air passages, usually provided inall faces of the box. Ripening of fruit in the boxes, while offeringconvenience and avoidance of injury, nevertheless poses the severeproblem of attaining uniform ripening conditions within the boxes due tothe heat buildup created by the fruit during ripening and theinaccessibility of the gaseous treating atmosphere to each fruit.Ripening in a boxed condition would also be expected to addsubstantially to the time of ripening, thus seeming to defeat attemptsto speed up the ripening cycle.

Ideally, therefore, any ripening process should permit the ripening ofboxed fruit without any undesirable loss in uniformity of treatingconditions and, importantly, reduce rather than add to the ripeningtime. The present discovery attempts to achieve these goals.

It has been found desirable to ripen the bananas and other fruits in aripening program wherein the boxed fruit is subjected to a firstinitiation stage to initiate the biochemical reactions for ripeningsimultaneously in every banana or finger of every hand of bananas orwherein the fruit is subjected to such an initiation stage and then to asecond distinct stage for de-greening and maturing the bananas on everyhand of bananas evenly or uniformly. To achieve the full benefit of thefruit so ripened and attain a long shelf life, the fruit may besubjected to a terminal low temperature stage of ripening. Each of thesestages requires different careful regulated temperature ranges and timescheduling to achieve the proper initiation and rate of biochemicalreactions and produce bananas uniformly having proper balance oftexture, color, flavor, aroma and holding quality. The 59 to 65 F.temperature range customarily used in present ripening rooms at thewarehouse represents a compromise for all of the biochemical reactionsand thus is not the ideal range for any one stage.

It has also been found that faster and more uniform ripening of boxedgreen tomatoes, customarily having a variety of states of ripeness andripening rates, and attainment of longer shelf life properties, can beachieved by similarly subjecting the tomatoes to distinct sequentialstages of initiating, de-greening, and terminal low temperatureripening, at selected, accurately controlled temperatures and times andwith introduction of controlled amounts of ethylene during theinitiating stage. Other fruits, such as peas, avocadoes and melons,including honeydew and the like, and some vegetables, having comparableripening reactions and characteristics, may be beneficially ripened in asimilar manner at faster ripening rates to attain greater uniformity ofripeness and longer shelf life properties.

An object of the present invention is the provision of a novel processand apparatus for accelerating the ripening of boxed bananas, tomatoes,and comparable fruits in a ripening program having a first initiationstage under selected conditions of temperature and time which results inuniform initiation of ripening and more rapid ripening of the fruit tomaturity.

Another object of the present invention is the provision of a novelprocess and apparatus for accelerating the ripening of boxed fruits in aripening program having two distinct stages of ripening including afirst initiating stage and a second de-greening and maturing stage, eachhaving selected conditions of temperature and time.

Another object of the present invention is the achievement of long shelflife in boxed fruit ripened in two distinct stages, as described in theimmediately preceding paragraph, and then maintained through a selectedlow temperature holding stage.

Another object of the present invention is to provide a process for theinitiation of ripening of each boxed banana, tomato or like fruitsimultaneously by subjecting such fruit to a controlled atmospherewithin a specific range of temperature for a limited time.

Yet another object of the present invention is the provision ofinitiation of ripening of unripe boxed fruit with the application ofrelatively high heat under forced air conditions, thereby avoidingnon-uniform high heat areas.

A further object of the present invention is the provision of a processfor attaining greater uniformity in ripening of boxed fruit bywithholding progression of the ripening of a fruit that has previouslybegun a natural ripening process and simultaneously initiating theripening of other fruit which has not begun any ripening in order toattain more uniformity.

Another object of the present invention is the provision of novelapparatus for ripening boxed fruit, especially bananas, in propersequence under automatic control in retail stores.

Still another object of the present invention is the provision ofautomatically controlled banana ripening matically controlled and cycledforced air heating and cooling facilities and ethylene gas introductionmeans for ripening bananas to a condition for retail sale at a morerapid rate.

Other objects, advantages and capabilities of the present invention willbecome apparent from the following detailed description, taken inconjunction with the accompanying drawings illustrating a preferredembodiment of apparatus for carrying out the invention.

BRIEF DESCRIPTION OF THE FIGURES FIG. 1 is a perspective view of fruitripening apparatus embodying the present invention; I 7

FIG. 2 is a vertical longitudinal section view'of the apparatus, takenalong the line 2-2 of FIG. 1;

FIG. 3 and 4 are vertical transverse section views of the apparatus,taken along the lines 3-3 and 44, respectively, of FIG. 2;

FIG. 5 is a horizontal section view of the apparatus, taken along theline 5-5 of FIG. 2;

FIG. 6 is a fragmentary, diagrammatic view of the tank, conduit andcontrol system for controlled supply of a mixture of ethylene andnitrogen gas to the ripening chamber of the apparatus;

FIG. 7 is a side elevation view, with parts broken away of theevaporator pan assembly employed in the apparatus for avoidingundesirable accumulations of liquid condensate in the apparatus, and

FIG. 8 is a schematic electrical diagram of the electrical controlcircuit employed in the apparatus.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE APPARATUSReferring to the drawings, wherein like reference characters designatecorresponding parts throughout the several figures, the apparatus forripening fruit in accordance with the present invention is constructedin the form of an upright storage case 10 of generally rectangularconfiguration designed to be placed at any convenient location in theback storage room of a retail establishment and having a height, forexample, of about 6% feet. In the illustrated example, the storage case10 comprises a base frame 11 made up of longitudinal channel beams 11aand transverse channel beams 11b, sidewalls l2 and 13, rear wall 14 andfront wall 15, each formed of insulated panels of any desiredconventional construction and secured at their lower portions to thebase frame 11 and along their vertical edges to vertical angle ironcomer frame members 16. A top wall 17 of similar panel construction issecured to horizontal top angle iron frame members 18, to form a sealedenclosure collectively with the side, rear and front walls. Preferably,the various wall members are secured to their associated frame membersby screws extending through the frame members and into the wall membersfrom the inside of the case to facilitate sealing of the case andminimize the possibility of the gases in the case from becomingdissipated through leaks.

The interior of the case is sub-divided by vertical partition panels 19and 20, constructed in the manner similar to the panels forming theouter walls of the case, into a ripening compartment or chamber 21,located between the partition 19 and sidewall 13, and intermediate airtreating chamber 22 between the partitions 19 and 20, and aninstrumentation chamber, generally indicated at 23, located between thepartition and endwall 12. In a preferred example, the instrumentationchamber is sub-divided by vertical partition 23c and horizontalpartition 24 into an upper chamber portion 23a, a lower chamber portion23b, and a vertically elongated chamber portion 23d.

Preferably the sidewall 12 bounding the instrumentation chamber 23 ishinged along one vertical edge thereof and provided with a handle andlatch set to permit opening of the sidewall 12 for servicing access tothe instrumentation chamber 23 and adjustment of the instrumentalitiestherein. Also, the front wall 15 is provided with a door opening 25which is approximately coextensive with the height and width of theripening compartment 21, and a pair of hinged doors 26 for closing thedoor opening 25 having suitable sealing strips around the perimeters ofthe doors to maintain an effective seal when the doors are closed.

The ripening compartment 21 is designed to house plural stacks of fruitboxes having apertured box walls, and is provided with a false bottom orfloor 27 having apertures 27a for passage of return air through thefloor 27 into the air return space 28 provided below the floor, forexample, by supporting the floor 27 on a frame of channel-shaped members29 resting on the base frame 11 or, as shown in the illustratedembodiment, on horizontal angle iron members 30 resting on the uppermostflanges of the base frame members 11. Sub-floor panels 30a may beprovided at the top plane of the base frame 11 defining the bottom ofthe air return space 28. Peripherally flanged, channel-shaped rails 31may also be provided on the bottom or floor 27 at suitable locations tosupport the lowermost fruit box of each stack of fruit boxes in spacedposition slightly above the plane of the floor 27.

Air and gases returned from the ripening compartment 21 through theopenings 27a in the floor 27 into the air return space 28 are admittedinto the air treating chamber 22 through air return opening 19a in thelowermost portion of the partition 19 and are drawn upwardly into inletopenings in a pair of double squirrel cage blowers 32 mounted in theupper region of the air treating chamber 22 and having their airdischarge outlets communicating with air supply openings 19b in theuppermost portion of the partition 19 to discharge the air and gaseslongitudinally horizontally across the ripening compartment 21immediately below the top wall 17. Disposed below the blowers 32 withinthe air treating chamber 22 is an evaporator or cooling coil 33 ofconventional construction, for example, an elongated fin and tubeevaporator coil, to cool the air rising from the air return opening 19ato the blowers 32. The evaporator coil 33 is intercoupled with aconventional compressor-condenser unit 34 located in the lowersubcompartment 23b of the instrumentation chamber 23 to form aconventional refrigeration system. The hinged sidewall 12 for theinstrumentation chamber 23 is provided with suitable ventilationopenings or louvres, indicated at 12a in FIG. 1, and the front wall 15may be similarly provided with ventilator louvres 15a in the region ofthe sub-compartment 23b to provide for suitable ambient air circulationabout the compressor-condenser unit 34.

Below the evaporator coil 33 and positioned to collect any liquidcondensate that may be gravity discharged therefrom is a drain p an 35having a drain tube 36 extending from the bottom thereof into thesub-compartment 23b to discharge the liquid condensate received by thepan 35 into a condensate evaporator 37.

As is more clearly illustrated in FIG. 7, the condensate-evaporator 37comprises an upwardly opening receptacle 38 below the discharge end ofthe drain tube 36 having an electrical resistance heater element 39, forexample, of the sheathed hair pin loop type conventionally employed inwater heaters, urns, and the like, supported in one end wall of thereceptacle 38. The electrical supply to the heater element 39 throughthe supply conductor 40 is controlled by a snap-action switch 41 mountedon a suitable: bracket fixed to the receptacle 38 and having a switchactuating lever 41a depending along an appropriate path into thereceptacle 38 and connected to a float 42. The float normally rests on asupporting member 43 fixed to the bottom of the receptacle 38 to supportthe float at a selected level spaced above the bottom of the receptacle38, and upon elevation of the level of the float 42, when the liquidcondensate level in the receptacle 38 reaches a selected level, theactuating lever 41a is pivoted upwardly a sufficient distance to closethe switch 41 and complete the supply circuit through the conductor 40to the heating element 39. The heat generated by the heating element 39boils off the liquid condensate in the receptacle 38 until asufliciently low liquid level is restored in the receptacle to positionthe float 42 so that the switch 41 is opened. The vapor phase condensatethus boiled off from the condensate evaporator is conveyed to theoutside of the case by the air currents flowing through the vents 12aand 15a and the subcompartment 23b about the compressor-condenser unit.With this condensate collecting and evaporating system, the troublesomeproblem of disposing of liquid condensate is alleviated withoutrequiring any special water disposal plumbing connections to beavailablein the storage room where the case is to be located.

An electrical heater of conventional construction, indicated by thereference character 44, is also located in the air treating chamber 22below the blowers 32 and in a position to give off heat to the air beingreturned from the air return openings 19a to the blowers for elevatingthe temperature of the air being recirculated to the ripening chamberwhen conditions so require.

The upper sub-compartment 23 houses a plurality of adjustable thermostatunits, collectively indicated by the reference character 45 in FIG. 2and described in greater detail hereinafter, connected to remotetemperature sensing bulbs 46 located in the ripening chamber 21, forexample, adjacent the top of the partition 19, as shown in FIG. 2. Anelectrical panel box 47 also located in the sub-compartment 23a housesthe electrical control circuitry, to be later described.

In the rearmost portion of the instrumentation chamber 23, for example,separated from the sub-compartments 23a and 23b by a vertical partition230, is the sub-compartment 23d for conveniently housing a tank orcommercial cylinder 48 containing a mixture of ethylene and nitrogengas, as later described in greater detail, and an outlet conduit system49 leading from the cylinder 48 through the conventional manual controlvalve 50 to an outlet nozzle 51 terminating in the ripening chamber 21,for example, at the uppermost portion of the partition 19. lnterposed inthe conduit system 49 are a regulating valve 52, having meters 53 and 54connected thereto for indicating the tank pressure and the regulatedpressure, a flow meter 55, and a solenoid valve V to be later described.

A schematic diagram of an electrical control circuit suitable forcycling the ripening apparatus through the initiating stage, thede-greening and maturing stage, and the terminal low temperature stagewhile automatically regulating the temperature within the ripeningchamber at the desired levels and admitting the mixture of ethylene andnitrogen gas to the ripening chamber during the initiating stage, isillustrated in FIG. 8. Referring to FIG. 8, the control circuit employsa pair of timers TI-l and TI-2, which are preferably of a commerciallyavailable type having a manual push button by which a clutch on eachtimer is engaged to effect driving of the timing mechanism through itstiming cycle and having manually adjustable means for setting thedesired period. As shown in FIG. 8, the terminal of the timer TI-1associated with the normally open upper contact is connected to thetimer motor M-1, to the coil of the solenoid valve V, controlling theflow of the mixture of ethylene and nitrogen gas from the cylinder 48 tonozzle 51, and is also connected to a red lamp L-l on the front wall ofthe case to energize the lamp L-l'when the timer TI-l is going throughits timing cycle. The lower normally open contact of the timer TI-1 isconnected to the thermostat T-l, set, for exam-- ple, on 75 F., andconnected in series with the coil of control relay CO1, and thisterminal is also connected through thermostat T-2, having a setting, forexample, of 80 F., to one side of the motor starter MS1 whose contactsMS-lA and MS1B control the compressor motor MC. The contact CO-1A andCO-lB of the control relay CO1 control the heater 44 in the air treatingchamber 22 of the case.

The upper normally open contact of timer TI-2 is connected to the motorM2 of that timer and to a lamp L-2, for example, an amber lamp, toindicate when the timer TI-2 is going through its timing cycle. Thenormally closed upper contact of timer TI-2 is connected to green lampL-3 to indicate when the timer TI2 has completed its timing cycle.Thermostats T-3 and T4 are connected to the lower normally open contactof timer TI-2, thermostat T-3 being set, for example, at 67 F., andbeing connected to the coil of relay CR-l, and thermostat T-4 being setat 56 F. and being connected to the coil of relay CO1. The contact CR1Aand CR-lB of the relay CR-l are connected, as shown, with the thermostatT-S, also set at 56 F., and with the motor starter MS-l.

Upon closing the circuit breaker CB in supply lines L-l and L-2connected to a nominal 220-volt supply and closing of the manual blowerswitches MMS1 and MMS-Z, the blowers 32 are energized to start aircirculating through the air treating compartment 22 and into theripening chamber 21. The ripening cycle is started by pushing the startbuttons on each of the timers TI-] and TI-2. Assuming the timer TI-l isset on 22 hours, as a specific example, upon energizing the timer bypushing the start button, the contact arms shift upwardly from theposition illustrated in FIG. 8, energizing the solenoid V, and theindicator lamp L-l. The

solenoid V, stays energized for the duration of the time set on timerTI-l, allowing the mixture of ethylene and nitrogen (for example, 6percent ethylene and 94 percent nitrogen) to flow into the ripeningchamber 21 at a selected rate (for example, 0.1 SCFH). During the timingcycle of timer TI-l, the thermostat T-I controls the heater 44 byenergizing and de-energizing the relay CO-] to maintain the temperaturein the ripening chamber 21 in accordance with the thermostat setting.Also, during the timing cycle of 'II-l, the thennostat T2 will closeshould the temperature in theripening chamber 21 rise above and energizethe starter MS-l, closing its contacts MS-lA and MS-lB to start therefrigeration system compressor motor MC. As soon as the temperaturereduces to the setting of the thermostat T-2, the thermostat will openand de-ener' gize the motor starter MS] to stop the compressor.

As soon as the timer TI1 times out, the timer TI-2, which may be set on38 hours as a specific example, is energized by the falling of the uppercontact arm of timer TI-l into engagement with the upper normally closedcontact thereof, supplying current to thermostat T-3 and energizing thecoil of relay CR-l. This closes the contacts CR-lA and opens contactsCR-lB, energizing the motor starter MS-l to start the compressor motorMC and lower the temperature within the ripening chamber 21 to thetemperature setting of the thermostat T3. The cycle of timer TI2continues for the duration of the time set on the timer. Should thetemperature in the ripening chamber 21 fall below the setting on thethermostat T4, the thermostat T-4 will close and energize the relayCO-l, which closes its contacts CO-lA and CO-1B to energize the heater44 and elevate the temperature of the air being supplied through blowers32 into the ripening chamber 21.

As soon as the second timer TI-2 times out, current is supplied throughthe normally closed contacts CR1B and thermostat T-5 to the motorstarter MS-l, closing its contacts MS-la and MS-lb and starting thecompressor motor MC. This establishes the third or terminal lowtemperature cycle, and this holding cycle will continue until anotherripening cycle is started by pushing the start buttons on timers TI-land TI-2 or until the main circuit breaker CB is turned off.

It will be apparent that the timers TI-l and TI-2 should have asufficient variation in timing cycle range to permit their adjustment toany'of the desired times for the initiating stage and the de-greeningand maturing stage, as described hereinafter in the more detaileddescription of the process and examples thereof. For example, the timerTI-l should be adjustable to any time up to about 30 hours and the timerTI-2 should be adjustable to time out cycles up to about 60 hours.Similarly, the range of adjustment of the temperature settings for thethermostats T-l to T-5 should cover a sufficient range to permitsettings to the various temperatures or temperature ranges indicated inthe ensuing detailed description of the process.

DETAILED DESCRIPTION OF THE PROCESS The present process achieves astartling rapid ripening of fruit and attains the capability of longershelf life for the fruit so ripened. This process is applicable tobananas, tomatoes, peas, avocadoes, melons (such as honeydew melons),and vegetables and, broadly, any

fruit that may have comparable ripening characteristics. The processutilizes the apparatus described above and includes the basic andessential step of initiating a controlled automatic ripening. Thisinitial and key process step forming an important aspect of thisinvention is the initiation of the ripening of unripe fruit under highuniform temperature conditions enabling the subsequent ripening toproceed rapidly without loss of quality. Thereafter, the de-greening ormaturing of the fruit may be achieved in a second step or stage. To thenobtain the full advantages of the ripening in accordance with the firsttwo stages, primarily among which are long shelf life and good storagecharacteristics, the fruit may be subjected to a third stage of selectedtemperature conditions.

In order to ripen a fruit, such as a banana, it must undergo biochemicalchanges that precede visible ripening. Such changes are referred to hereas initiation of ripening and include (1) an ethylene induced depressionin respiratory rate; (2) changes in the synthesis of plant hormones, RNAand proteins, and (3) change from a depressed to a stimulatedrespiratory rate.

INITIATING RIPENING In its broadest aspects, it has been discovered thatthrough the present invention an initiation of ripening of boxed 'fruitsmay be forced by achieving and maintaining a fruit temperature withinthe range of 68 to 95 F. for a time between approximately 4 to 72 hoursin an atmosphere that may contain between 0.05 and 30,000 ppm ethylenevThe limits set forth for ethylene constitute the lowest effective rangeto achieve any of the advantages of the use of ethyleneand the upperlimit is fixed solely by reason of the explosiveness of mixtures ofethylene having greater concentration than 30,000 ppm.

During the initiation ripening stage, a biochemical 1 process is begunthrough the introduction of the ripen ing hormone ethylene. Within thespecific temperature range of 68 to 95 F. and within the specifiedethylene concentration, the protein hormonal production accelerates toachieve a rapid impetus toward ripening of the fruit. It is an importantadvantage of this invention that virtually every fruit in the box,regardless of the variety, achieves a simultaneous initiation of thisbiochemical process, thus assuring the greatest uniformity possible. Theboxed fruit, upon being subjected to the temperature specified and theethylene concentration, undergoes biochemical changes which, althoughsuch changes may not be visible even after completion of this stage,nevertheless enable the fruit to enter the next stage where ripeningnoticeably occurs within a time that would not have been possible exceptfor the previous initiation of ripening.

It is important for the success of the ripening procedures of thepresent invention that the times, temperatures, and concentration ofethylene be followed to prevent poor quality fruit at the end of theripening stage. A temperature higher than that specified, for instance,has been found to produce damage and injury to the peel, whereas lowertemperatures prolong the ripening process to an extent wherein animportant advantage, the economy of the present process, is lost. Theforced gaseous flow of air with ethylene and an inert diluent which isin continuous contact with the ill fruit in the boxes through theopenings in these boxes is a factor in achieving uniformity oftemperature within the boxes, and particularly with respect to the fruitlocated within the interior of the boxes.

The concentration of ethylene has been found to be variable and may bein as low a concentration as that providing a saturation of the ethylenehormones for the most effective initiation. It has been found that inpractical application, continuous injection of the ethylene gas withnitrogen or other inert gas up to about 95 percent assures safety andalso provides a more uniform exposure of the fruit to ethylene.

RIPENING In the second stage, which may be referred to as the actualripening stage, wherein actual de-greening or maturing occurs,thetemperature must be maintained within a range between 58 and F. for atime between 10 and 96 hours. In the ripening stage. no ethylene shouldbe used, since such further hormonal addition may reduce the quality ofthe fruit.

In the ripening stage, there is a great increase in respiratory ratewhich at its maximum is often as high as seven times that of greenuninitiated fruit. The fruit, though still green, has now beenirreversibly initiated to ripen. Heat is produced in conjunction withthe rise in rate of respiration. During this stage the enzymes of thecell, or its biochemical machinery, are being freed or synthesized tomake possible the many changes which will occur in the latter part ofthis stage. Phosphorus and other inorganic minerals move freely as cellwall and cell organelle permeability increase. l-lemicellulosehydrolysis begins and active tannin destruction occurs. These tanninsincidentally are responsible for the astringency of green fruit. Adecrease'in protopectin in the middle lamella of cells also takes placealong with an increase in soluble pectin, which is associated withsoftening.

All of these previously mentioned changes continue into the period wherechlorophyli degradation becomes apparent. Heat production andrespiratory rate quickly reach their maximum and softening occurs. Otherchanges are the conversion of starch and additional hemicellulose tosucrose, glucose, and fructose; the synthesis and freeing of vitamin Cand other vitamins; the degradation of active tannins; completion of theconversion of protopectin to soluble pectin the synthesis of carotenes;the production of malic acid and other organic acids; the qualitativechange in lipids and fatty acids; an increase in osmotic pressure;increase in respiratory quotant, and synthesis of flavor constituents.

After passing through the high temperature initiation of ripening stageand the ripening or de-greening stage, the fruit is in an acceptablestate for consumption, although preferably the fruit would be about oneday early in maturity if the fruits are to be displayed to the public.Thereafter, it is preferable, though not essential, that the fruit bemaintained at a temperature of 56 to R, which will assure a ratherlengthy storage life up to as much as two weeks.

While broad ranges have been set forth for the processing of many fruitsaccording to the present in vention, for particular fruits certain morespecific ranges have been found to be desirable. Particularly peratureshould be 72 to 75 F. The time for the initia- 5 tion is found to bepreferably within 18 to 24 hours, but may extend within 4 to 35 hours.The concentration of ethylene is most efficient when maintained between25 and 1,000 ppm, although concentrations of 0.05 to 30,000 arepermitted.

In the ripening or de-greening stage with bananas, it has been foundthat a temperature range of 58 to 75 F., and more preferably 66 to 70F., is particularly advantageous. The time for the bananas within theripening stage may extend between 10 and 96 hours, but more preferably20 to 40 hours.

These temperatures are important to achieve high quality ripenedbananas. If the temperature is too high, certain reactions are fasterthan they should be and poor quality ripe fruit results. This givesfruit with offflavors a short shelf life and a peel which very easilydevelops injuries and black or brown areas. The pulp softens rapidly. Iftoo low a temperature is used during stage two, the pigments and tanninscontinue their ripening changes faster than the starch to sugarconversions, organic acid changes or synthesis of flavor constituents.Thus the ripe fruit appears riper than its eating qualities wouldindicate. This results in flavorless fruit, lacking in sweetness andorganic acids, as well as a mealy texture. The forced air flow inaccordance with this invention assures the necessary uniformity oftemperature of the boxed fruit and avoids hot spots.

After the bananas have undergone the foregoing two stages, if they aremaintained at a temperature of 56 to 80 F., and more particularly 60 to70 F., a storage life of up to 10 days to 2 weeks is permissible. Such ashelf life enables the fruit merchandiser to display the bananas for asubstantially longer period of time without fear of spoilage than hadever been achieved by any previous process.

Specific examples of the process of the present invention utilizing thepreviously described apparatus are as follows:

EXAMPLE I Fruit Time for Temperature Initiation Ethylene Fruit Varieties(F.) (hrs) (ppm) l. Valery Lacatan 85 9 5 I Giant Cavendish 80 ll I00and other 70 16 5 I00 Cavendish type 65 22 5 100 fruit 60 37 5 lOO II.Gros Michel and 85 6 5- I00 Cocos 80 7 5 I00 70 l l 5 I00 65 I6 5 100 6024 5 100 NOTE:

A. The ethylene concentration fluctuated substantially, due to leaks.The ethylene gas was therefore continuously introduced, resulting in anaverage concentration of about 25 ppm.

B. All fruit was packed in the usual cardboard boxes of 40 lbs.capacity, with openings on the top and all sides.

After the initiation of the ripening, the bananas pass through thesecond stage during which visible organic ripening changes occur due tothe enzyme synthesis. The following example is illustrative:

EXAMPLE II Two portions of the initiated bananas from Example I,identified as Group I and Group II, were subjected to temperatures of 60F. for 96 hours and 72 F. for 36 hours and upon completion of thissecond or ripening stage, the bananas of both groups were found to beabout color 3-4, which is exactly the degree of ripeness most acceptableto fruit merchandisers for display. Taste and aroma of these bananaswere excellent.

In order to maintain as long a shelf life as possible and to achieve themaximum from the preceding ripening stages, the treated bananas wereheld at a temperature 60 F. for l0 days. During this entire period oftime, the bananas were found to be of good marketable quality andacceptable to any fruit merchandiser for sale to the public.

The present invention is also particularly applicable to tomatoes, sincetomato ripening is quite similar to the ripening of bananas. To initiateripening in to matoes, the fruit temperature range should be from 68 to95 F., preferably 72 to 92 F. while in an atmosphere containing ethylenein an amount between 0.05 and 30,000 ppm, preferably 25 1,000 ppm, for atime that may be between 24 and 72 hours.

In the ripening stage the tomatoes are to be held at a fruit temperatureof 58 to 72 F., preferably 60 to 72 for a time between 24 and 96 hours,or preferably 60 to 96 hours without need of any ethylene concentration.

Tomatoes, after passing through the two distinct stages may then be keptup to as long as 2 weeks at a temperature between 58 and 80 F. orpreferably 60 to 72-F. Such a shelf life is totally unique to any fruitmerchandiser.

A specific example illustrating the effectiveness of the presentinvention for tomatoes is as follows:

EXAMPLE III Twenty boxes of 6 X 6 and two boxes of 5 X 5 Pearson EarlyPack tomatoes, Meyers Pride" from King City, California were picked,washed, graded, and waxed. The fruit was divided into Groups I and II.

GROUP I Twenty boxes 18 of 6 X 6 and two of 5 X 5) were initiated for 64hours at 83 F. with between 10 and 20 ppm ethylene delivered as 0.1 SCFHof 6 percent ethylene in nitrogen. (The nitrogen was added only as asafety precaution.) The fruit in three boxes was marked individually asto their color grade. After the initiation period, the ethylene flow wasstopped and the temperature cycled to F. The fruit was held at thistemperature for an additional period to the total times shown in Table Ibelow:

One box was held at 72 F. with no ethylene for the entire period. Thisserved as a control to indicate ripening without initiation.

The results of the treatment of the tomatoes in ac cordance with theprocedures set forth for Group II are set forth in Table 11:

TABLE II RIPENING OF TOMATOES IN AIR AT 72 F. (GROUP 11) Total Time(hrs) Percent having each color number 1 2 3 4 5 6 Rotten From theTables it will be evident that the procedure of the present inventionproduced a far more uniform ripening of the tomatoes where it can beseen that the substantial majority of the tomatoes are of a group 4coloring that is, a substantially red color with little, if any, greenand none of the No. 6 color which is the deep red attained just prior tosubstantial softness characteristic of a rotten fruit. Also, most of thefruit is in at least color No. 3, meaning that some red appears on thetomato. In contrast, the tomatoes of Group II are clearly seen to be ofno uniformity, having spread substantially across the color scaleincluding a few rotten tomatoes. From the above, it may be stated thatthe treatment in accordance with the present invention produceddesirable commercially acceptable tomatoes for immediate display andsale.

The tomatoes of Group I were able to be kept at a temperature of between58 and 60 for up to 2 weeks in display, during which time the tomatoeswould be found to have good color, texture, and flavor, and not beoverly ripe or too soft.

In accordance with another aspect of the present invention, it wasdiscovered that tomatoes which have achieved some initiation of ripeningthat may have oc-. curred due to maturity of the fruit, may be retardedin further ripening, while the tomatoes within the same group that maynot have initiated ripening may be forced into an initiation of ripeningso that a greater uniformity may be achieved between the tomatoes.Through the use of higher temperatures in the initiation of ripeningcycle, it was discovered that particularly high heat within a narrowrange would inactivate fruit already initiated, and thus, when all ofthe fruit would subsequently pass through the second stage or ripeningstage, there would be produced more uniform color grades of 2 to 4presently considered desirable by the fruit merchandiser for initialdisplay for the customer. The inactivation of the fruit which may havepreviously been initiated is based upon the discovery that at atemperature above 86 F., the red pigment, lycopene, will not be producedin the tomato. At a fruit temperature range of over 86 to F., therefore,previously initiated fruit will not progress in a ripening stage.However, the temperature is such that in the presence of ethylene, aspreviously described, there will be produced an initiation of theripening, forcing the previously unripe and uninitiated fruit to bebrought closer in maturity to the unripe, butripening, or previouslyinitiated fruit. The following experiment illustrates the manner inwhich uniform ripening may be readily achieved:

EXAMPLE 1V GROUP 1 Twenty boxes with the usual openings were placed inthe apparatus of this invention and ripening initiated for 48 hours at87 F. pulp temperature with 10 17 ppm ethylene from 6 percent ethylenein nitrogen flowing at 0.1 SCFI-l into the openings in the box. Afterthis the machine cycled to 71 F. without ethylene for 48 hours, at theend of which four boxes were removed at random and color graded andplaced back inside the machine. At this time the machine was cycled to63 F. for the remainder of the experiment. At 9 days, 15 of the boxeswere removed and the other five continued in the chamber.

GROUP II One box was placed in a tent with air, without ethylene, at 72F.

The groups were placed in their chambers with no sorting or extrahandling of any kind and were left untouched until the fourth day when20 percent of the boxes in the machine were color graded along with thecontrol and then not touched until the ninth day, when 10 percent morewere graded along with the ones previously graded.

The fruit was rated for color on the fourth, eighth and 14th days. TableII summarizes these results.

TABLE 11 Percent of Tomatoes in Each Color Grade Present Invention(Group I) The most striking and significant results are r indicated withthe fruit in Group I of EXAMPLE IV. The

87 held back the faster ripening fruit, while at the same timeaccelerating the initiation of the slower ripening fruit. It, therefore,served as an equalizer of fruit variability. Color development occurredafter the temperature was reduced. After four days 89.8 percent of thefruit was in color grades 2 and 3, or the pink stage desired by markets.Without this temperature sequencing, 40.3 percent of the fruit was inthis pink stage.

The present process significantly reduced the percentage of rottingfruit both during ripening and during holding. The fruit which startedrotting first served as a source of infection for adjacent fruit. Thus,if rotten fruit was not progressively sorted out, it greatly amplifiedthe rotting (more than doubled the percent of rotten fruit).

The carbon dioxide concentration in the apparatus varied between 0.01percent and 0.09 percent during the experiment. The ethyleneconcentration varied between 10.3 ppm and 19.2 ppm during the initiationcycle.

It has also been discovered that longer shelf life has been obtainedwhen the fruit was initiated to ripening in air and ethyleneconcentration, but maintained at a low oxygen concentration during thesecond or ripening stage. The most important period for obtaining theprolonged shelf life was found to be 3 to 5 days following theinitiation when most of the respiratory and biochemical action ceased.The presence of ethylene in an amount previously found desirable, ifused during the second or ripening stage, in an amount between 0.05 and30,000 ppm while maintaining a concentration of oxygen between about 0.5and 2.5 percent, and preferably 0.8 1.5 percent, by volume standardconditions is effective. Low oxygen concentrations were found to besignificant only during the ripening or second stage. The presence ofethylene during this second stage helped to accelerate the changes andincrease the rate of ripening and the length of shelf life. While theresults were not as satisfactory without the presence of ethylene withthe low concentration of oxygen in the ripening stage, there wasnevertheless approximately 50 percent gain in shelf life through thecombination of low oxygen atmosphere and ethylene during ripening stage.The effectiveness of low oxygen concentration was found to exist forbananas or tomatoes or other comparable fruits.

It should be manifest from the foregoing description of the process thatcomplete control over the ripening of fruits is achieved and,importantly, (a) the entire ripening process is accelerated, while (b)the shelf life may be extended substantially beyond the several dayscommonly experienced to a period as long as to 14 days. Obviously, theadvantages accruing to the fruit merchandiser are numerous including thesubstantial reduction in warehousing and ripening rooms, and,importantly, substantial reduction in the spoilage of the fruit. Not tobe overlooked is the fact that uniform color quality, including tasteand appearance, are also readily obtainable for the first time.

What is claimed is:

1. Apparatus for automatically ripening fruits, such as bananas and thelike, through a selected ripening program, comprising a casing havinginsulated wall means defining a ripening chamber providing a closedspace to contain a quantity of the fruit to be ripened while the spaceis conditioned through said selected ripening program, means within saidcasing defining an air treating chamber having air return and supplypassages communicating with said ripening chamber, blower means forcirculation of air in a closed loop path serially through said airtreating chamber and ripening chamber, refrigeration means including acooling coil in said air treating chamber for cooling the aircirculating therethrough, said air treating chamber including heatingmeans for heating the air circulating in said path, means including asolenoid regulating valve for selectively supplying ethylene gas intosaid ripening chamber, first and second timer switch means each settableto a selected range of time periods, first and second thermostat meansresponsive to the temperature in said ripening chamber and respectivelycoupled from said first timer switch means to said refrigeration meansand to said heating means for automatically activating saidrefrigeration means and heating means to maintain a first selectedtemperature range in said ripening chamber throughout a firstconditioning stage in said ripening program for a time durationdetermined by the setting of said first timer switch means, meansconnecting said first timer switch means with said solenoid regulatingvalve for conditioning the latter to admit ethylene gas therethrough ata selected rate during said first conditioning stage, third and fourththermostat means responsive to the temperature in said ripening chamberand respectively coupled from said second timer switch means to saidrefrigeration means and to said heating means for automaticallyactivating said refrigeration means and heating means to maintain asecond selected temperature range below said first temperature rangethroughout a second conditioning stage in said ripening program for atime duration determined by the setting of said second timer switchmeans, and means interconnecting said first and second timer switchmeans to condition the second timer switch means to enable said thirdand fourth thermostat means to activate said refrigeration means andsaid heating means only after said first timer switch means has timedout said first conditioning stage.

2. Apparatus for automatically ripening fruits as defined in claim 1,including fifth thermostat means conditioned by said second timer switchmeans when the latter has timed out said second conditioning stage foractivating said refrigeration means to maintain a selected thirdtemperature range in said ripening chamber during a third conditioningstage of said ripening program.

3. Apparatus for automatically ripening fruits as defined in claim 1,wherein said casing includes a compartment having a storage tankcontaining ethylene gas under pressure therein, and said means forselectively supplying ethylene gas to said ripening chamber includingoutlet conduit means communicating with said tank having a dischargenozzle located in said ripening chamber and including said solenoidregulating valve between said tank and said nozzle.

4. Apparatus for automatically ripening fruits as defined in claim 1,including an upwardly opening drain pan in said air treating chamberlocated below said cooling coil to receive any liquid condensate whichswitch means activated by said float means for energiz ing said electricheater means when said float means indicates a selected liquid level insaid receptacle.

5. Apparatus for automatically ripening fruits as defined in claim 1,wherein said first timer switch means is settable to time periods of upto about 72 hours and said second timer switch means is settable to timeperiods up to about 192 hours.

1. Apparatus for automatically ripening fruits, such as bananas and thelike, through a selected ripening program, comprising a casing havinginsulated wall means defining a ripening chamber providing a closedspace to contain a quantity of the fruit to be ripened while the spaceis conditioned through said selected ripening program, means within saidcasing defining an air treating chamber having air return and supplypassages communicating with said ripening chamber, blower means forcirculation of air in a closed loop path serially through said airtreating chamber and ripening chamber, refrigeration means including acooling coil in said air treating chamber for cooling the aircirculating therethrough, said air treating chamber including heatingmeans for heating the air circulating in said path, means including asolenoid regulating valve for selectively supplying ethylene gas intosaid ripening chamber, first and second timer switch means each settableto a selected range of time periods, first and second thermostat meansresponsive to the temperature in said ripening chamber and respectivelycoupled from said first timer switch means to said refrigeration meansand to said heating means for automatically activating saidrefrigeration means and heating means to maintain a first selectedtemperature range in said ripening chamber throughout a firstconditioning stage in said ripening program for a time durationdetermined by the setting of said first timer switch means, meansconnecting said first timer switch means with said solenoid regulatingvalve for conditioning the latter to admit ethylene gas therethrough ata selected rate during said first conditioning stage, third and fourththermostat means responsive to the temperature in said ripening chamberand respectively coupled from said second timer switch means to saidrefrigeration means and to said heating means for automaticallyactivating said refrigeration means and heating means to maintain asecond selected temperature range below said first temperature rangethroughout a second conditioning stage in said ripening program for atime duration determined by the setting of said second timer switchmeans, and means interconnecting said first and second timer switchmeans to condition the second timer switch means to enable said thirdand fourth thermostat means to activate said refrigeration means andsaid heating means only after said first timer switch means has timedout said first conditioning stage.
 2. Apparatus for automaticallyripening fruits as defined in claim 1, including fifth thermostat meansconditioned by said second timer switch means when the latter has timedout said second conditioning stage for activating said refrigerationmeans to maintain a selected third temperature range in said ripeningchamber during a third conditioning stage of said ripening program. 3.Apparatus for automatically ripeNing fruits as defined in claim 1,wherein said casing includes a compartment having a storage tankcontaining ethylene gas under pressure therein, and said means forselectively supplying ethylene gas to said ripening chamber includingoutlet conduit means communicating with said tank having a dischargenozzle located in said ripening chamber and including said solenoidregulating valve between said tank and said nozzle.
 4. Apparatus forautomatically ripening fruits as defined in claim 1, including anupwardly opening drain pan in said air treating chamber located belowsaid cooling coil to receive any liquid condensate which may form on anddrip from exterior surfaces of said cooling coil, said casing includinga compartment spaced from said air treating chamber and ripening chamberin communication with ambient air, an evaporator receptacle in saidcompartment, drain tube means connecting said drain pan with saidreceptacle for conveying the liquid condensate received in said drainpan to said receptacle, electric heater means in said receptacle forboiling off condensate accumulating in said receptacle, float means insaid receptacle, and switch means activated by said float means forenergizing said electric heater means when said float means indicates aselected liquid level in said receptacle.
 5. Apparatus for automaticallyripening fruits as defined in claim 1, wherein said first timer switchmeans is settable to time periods of up to about 72 hours and saidsecond timer switch means is settable to time periods up to about 192hours.